Broadly defined, structured application-specific integrated circuits (ASICs) attempt to reduce the effort, expense and risk of producing an ASIC by standardizing portions of the physical implementation across multiple products. By amortizing the expensive mask layers of the device across a large set of different designs, the non-recurring expense (NRE) seen by a particular customer for a customized ASIC may be significantly reduced. There may be additional benefits to the standardization of some portions of mask set, which may include improved yield thru higher regularity and reduced manufacturing time from tape-out to packaged chip.
Structured ASIC products may be differentiated from other devices by the point at which the user customization occurs and how that customization is actually implemented. Most structured ASICs only standardize transistors and the lowest levels of metal. A large set of metal and via masks may still be needed in order to customize a product. This may result in only a marginal cost reduction for NRE. Manufacturing latency and yield benefits may also be compromised using this approach.
In another customizable ASIC technology, for example, as discussed in U.S. Pat. Nos. 6,194,912; 6,236,229; 6,245,634; 6,331,733; 6,331,789; 6,331,790; 6,476,493; 6,642,744; 6,686,253; 6,756,811; 6,819,136; 6,930,511; 6,953,956; 6,985,012; 6,989,687; 7,068,070; 7,098,691; 7,105,871; 7,157,937; 7,439,773; and 7,436,773 (all assigned to the assignee of the present application and incorporated by reference herein) one may, for example, standardize all but one via layer in the mask set. This single via layer may be implemented, for example, using one of two approaches:
A prototyping flow using direct-write e-beam technology eliminates the need for any mask layers. This may result in a zero-NRE product with short, fast turn around time.
A production flow using a mask layer for the vias, which may provide, for example, a 20× reduction in NRE for final production devices.
However, ASICs, and even many structured ASICs, may lack the field programmability of field-programmable gate arrays (FPGAs), which are another type of programmable logic device.